‘Dipstick’ in the brain could predict damage just in time

TO CHECK a car’s oil levels, use a dipstick. To check the brain has enough energy, we might be able to do the same, using a probe that can monitor fluid in the brain.

“The goal is to save brain tissue,” says Elham Rostami of the Karolinska Institute in Stockholm, Sweden. Last month, Rostami and 47 others published guidelines on how and when to use the technique, known as brain microdialysis, in the hope that more hospitals would adopt it (Intensive Care Medicine, doi.org/6k3).

The approach involves inserting a 1-centimetre-long probe directly into the brain. It measures levels of chemicals in the fluid that bathes cells, including glucose, the brain’s main energy source. When used on people in intensive care after a stroke or head injury, it warns doctors if glucose starts to dip – which can cause brain damage.

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The tool is widely available, but it is not clear yet whether the information it provides saves lives, meaning it is largely used for research instead.

But Rostami believes her use of the probe helped to save a woman’s life last year. The woman was in intensive care after a stroke that involved bleeding on the surface of her brain. The probe revealed that although the bleeding had stopped, the woman’s brain glucose levels were falling, probably because other blood vessels had constricted.

In response, Rostami’s team administered a drug to boost her heart rate and send more blood to the brain. The probe then showed glucose levels beginning to rise, and within hours the woman’s condition had improved. “She started responding to commands to squeeze my hand,” says Rostami. “It shows [the probe’s] potential to be used as a warning system.”

It may seem drastic to drill a hole in the skull and press a probe directly into brain tissue, but for seriously ill people it might provide vital clues that their brain is about to suffer damage.

Pressing a probe into brain tissue may seem drastic, but it might provide vital clues to imminent damage

People in intensive care are already hooked up to a host of monitors, which keep track of things such as heart rate and levels of glucose and oxygen in the blood. But finding out what’s going on inside a person’s head is much harder.

An electroencephalogram (EEG) can give a read-out of the brain’s electrical activity, while various kinds of scan can give a snapshot of its health, but a person in critical condition can’t remain inside a scanner all day. This is one advantage of the probe&colon; it can be used to get frequent readings relatively easily.

“Anything that gives us a better understanding of what’s going on in the brain after injury is a good thing,” says Karim Brohi, a trauma specialist at the Royal London Hospital. But he cautions that there are no figures yet on whether such monitoring does improve survival rates.

Because the technique is fairly new, its risks are not yet fully known. There have been no cases of the probe causing bleeding or damage to brain tissue, to Rostami’s knowledge, but to minimise potential problems it is generally placed on the right side of the brain. That’s because most people are right-handed, and the left side of the brain controls the right side of the body, as well as usually being more important for language.

This article appeared in print under the headline “Brain ‘dipstick’ can spot dangerous energy drop”